Rock Drill Oil

ABSTRACT

Provided is a lubricating oil composition suitable for use in rotary pneumatic and reciprocating tools, comprising a Fischer-Tropsch base oil, a friction modifier based on synthetic ester and a sulfurized extreme pressure agent. The present lubricating oil composition has superior wear, friction and extreme pressure characteristics.

TECHNICAL FIELD

Provided is a rock drill fluid comprised of a Fischer-Tropsch based oil(FTBO) and an additive package. More particularly, the Fischer-Tropschbase oil is blended with an additive package comprising a frictionmodifier based on synthetic esters and a sulfurized extreme pressureagent.

BACKGROUND

One of the key functions of any metalworking or rock drill fluid is toprotect tools, parts or machine equipment from wear. These fluids addvalue to an operation in several ways, including the extension ofequipment life, increased machining accuracy and the avoidance ofunnecessary shutdowns. A common strategy for formulating a lubricantwith good wear, friction and extreme pressure properties is to useadditives that further modify friction between moving parts and/orprotect metal surfaces. A common test used to benchmark the wear,friction and extreme pressure properties of a lubricant is the Falex EPtest (ASTM 3233A).

Often a non-detergent motor oil or a hydraulic fluid is used tolubricate pneumatic tools. However, this type of oil is inadequate forthe sophisticated and very-expensive tools of today. The demands of theconstant pounding or hard work of a rotary tool requires a lubricantthat can hold up much better than a hydraulic oil. The need for asuitable lubricating oil which exhibits the needed wear, friction andextreme pressure properties required by rotary pneumatic andreciprocating tools continues to exist.

SUMMARY

Provided is a lubricating oil composition suitable for use in rotarypneumatic and reciprocating tools, comprising a Fischer-Tropsch baseoil, a friction modifier based on synthetic esters and a sulfurizedextreme pressure agent. The Viscosity Index (VI) of the Fischer-Tropschbase oil used in the composition is generally at least 120. The presentlubricating oil composition has superior wear, friction and extremepressure characteristics.

Among other factors, the present lubricating oil is predicated on thediscovery that a Fischer-Tropsch base oil, when combined with a frictionmodifier additive based on synthetic ester, and a sulfurized extremepressure agent, provides one with a lubricating oil of exceptional wear,friction and extreme pressure properties as compared to moreconventional formulations. These properties are particularly seen whenmeasured by the Falex Pin and Vee Block Machine. The present lubricatingoil composition can therefore be readily used in rotary pneumatic andreciprocating tools, such as a rock drill or a jack hammer.

DETAILED DESCRIPTION

The term “comprising” mean including the elements or steps that areidentified following that term, but any such elements or steps are notexhaustive, and an embodiment can include other elements or steps.

The present lubricating oil composition is based on a Fischer-Tropschderived base oil. “Fischer-Tropsch derived” means that the product,fraction, or feed originates from or is produced at some stage by aFischer-Tropsch process. As used herein, “Fischer-Tropsch base oil” maybe used interchangeably with “FT base oil,” “FTBO,” “GTL base oil” (GTL:gas-to-liquid), or “Fischer-Tropsch derived base oil.” The feedstock forthe Fischer-Tropsch process may come from a wide variety ofhydrocarbonaceous sources, including natural gas, coal, shale oil,petroleum, municipal waste, derivatives and combinations thereof. TheFischer-Tropsch base oil used can be any suitable Fischer-Tropsch baseoil.

For example, in a number of patent publications and applications, i.e.,US2006/0289337, US2006/0201851, US2006/0016721, US2006/0016724,US2006/0076267, US2006/020185, US2006/013210, US2005/0241990,US2005/0077208, US2005/0139513, US2005/0139514, US2005/0133409,US2005/0133407, US2005/0261147, US2005/0261146, US2005/0261145,US2004/0159582, U.S. Pat. No. 7,018,525, U.S. Pat. No. 7,083,713, U.S.application Ser. Nos. 11/400,570, 11/535,165 and 11/613,936, which areincorporated herein by reference, a Fischer Tropsch base oil is producedfrom a process in which the feed is a waxy feed recovered from aFischer-Tropsch synthesis. The process comprises a complete or partialhydroisomerization dewaxing step, using a dual-functional catalyst or acatalyst that can isomerize paraffins selectively. Hydroisomerizationdewaxing is achieved by contacting the waxy feed with ahydroisomerization catalyst in an isomerization zone underhydroisomerizing conditions.

Fischer-Tropsch synthesis products can be obtained by well-knownprocesses such as, for example, the commercial SASOL® Slurry PhaseFischer-Tropsch technology, the commercial SHELL® Middle DistillateSynthesis (SMDS) Process, or by the non-commercial EXXON® Advanced GasConversion (AGC-21) process. Details of these processes and others aredescribed in, for example, EP-A-776959, EP-A-668342; U.S. Pat. Nos.4,943,672, 5,059,299, 5,733,839, and RE39073; and US PublishedApplication No. 2005/0227866, WO-A-9934917, WO-A-9920720 andWO-A-05107935. The Fischer-Tropsch synthesis product usually compriseshydrocarbons having 1 to 100, or even more than 100 carbon atoms, andtypically includes paraffins, olefins and oxygenated products. FischerTropsch is a viable process to generate clean alternative hydrocarbonproducts.

In one embodiment, the Fischer-Tropsch base oil used in the presentlubricating oil composition is of high viscosity index (VI). Generally,the viscosity index is at least 120, and in another embodiment, at least150. In one embodiment, the Fischer-Tropsch base oil has a VI greaterthan an amount determined by the equation: VI=28×Ln(Kinematic Viscosityat 100° C.)+95. The Fischer-Tropsch base oil can be used alone or can beblended with another Fischer-Tropsch base oil. Minor amounts, e.g., lessthan 50 wt %, of other conventional base oils, such as mineral basedoils and synthetic oils, can also be blended into the lubricating oil,as long as the wear, friction and extreme pressure properties of theoverall composition are not negatively affected.

Additives which can be blended with the Fischer-Tropsch base oil toprovide the lubricating oil composition, include those which areintended to improve the properties of wear, friction and extremepressure properties of the finished lubricant. Such additives arecommercially available, are known, and are available in commerciallyavailable packages. The additives for the present lubricating oilcomposition include a friction modifier, which is based on one or moresynthetic esters, and an extreme pressure agent. The extreme pressureagent is a sulfurized extreme pressure agent, but other extreme pressureagents can be used. In another embodiment, the present lubricating oilcomposition designed for use in rotary pneumatic and reciprocating toolsinclude an emulsifier and a copper corrosion inhibitor.

Other typical additives include, for example, anti-wear additives, EPagents, detergents, dispersants, antioxidants, pour point depressants,viscosity index improvers, viscosity modifiers, demulsifiers,antifoaming agents, rust inhibitors, seal swell agents, wetting agents,lubricity improvers, metal deactivators, gelling agents, tackinessagents, bactericides, fluid-loss additives, colorants, and the like.

In one embodiment, the total amount of additives in the lubricating oilcomposition will be approximately 0.1 to about 30 weight percent of thelubricating oil composition. However, since the Fischer-Tropsch baseoils can have excellent properties including excellent oxidationstability, low wear, high viscosity index, low volatility, good lowtemperature properties, good additive solubility, and good elastomercompatibility, a lower amount of additives may be required for thelubricating oil composition than is typically required with base oilsmade by other processes. The use of additives in formulating finishedlubricants is well documented in the literature and well known to thoseof skill in the art. In one embodiment, the Fischer-Tropsch oil willcomprise at least 70 wt % of the lubricating oil, and in anotherembodiment, at least 90 wt % of the lubricating oil composition. In yetanother embodiment, the Fischer-Tropsch base oil comprises at least 95wt % of the composition.

In one embodiment, the Fischer-Tropsch base oils may be obtained byusing a process comprising the steps of: a) performing a Fischer-Tropschsynthesis on syngas to provide a product stream; b) isolating from saidproduct stream a substantially paraffinic wax feed having less thanabout 30 ppm total combined nitrogen and sulfur, and less than about 1wt % oxygen; c) dewaxing said substantially paraffinic wax feed byhydroisomerization dewaxing using a shape selective intermediate poresize molecular sieve with a noble metal hydrogenation component whereinthe hydroisomerization temperature is between about 600° F. (315° C.)and about 750° F. (399° C.), whereby an isomerized oil is produced; andd) hydrofinishing said isomerized oil.

Alternatively, step d) of the above process may be changed to: d) hydrofinishing said isomerized Fischer-Tropsch oil, whereby a base oil isproduced having: a weight percent of all molecules with at least onearomatic function less than 0.30, a weight percent of all molecules withat least one cycloparaffin function greater than the kinematic viscosityat 100° C. in mm²/sec. multiplied by three, and a ratio of weightpercent of molecules containing monocycloparaffins to weight percent ofmolecules containing multicycloparaffins greater than 15.

Kinematic viscosity is a measurement of the resistance to flow of afluid under gravity. Many lubricating base oils, finished lubricantsmade from them, and the correct operation of equipment depends upon theappropriate viscosity of the fluid being used. Kinematic viscosity isdetermined by ASTM D 445-10. The results are reported in mm²/sec. In oneembodiment, the kinematic viscosities of the Fischer-Tropsch base oilsused in the present lubricating oil composition are between about 2mm²/sec. and about 20 mm²/sec., or they can be between about 2 mm²/sec.and about 12 mm²/sec.

Pour point is a measurement of the temperature at which the sample willbegin to flow under carefully controlled conditions. Pour point may bedetermined as described in ASTM D 5950-02 (Reapproved 2007). The resultsare reported in degrees Celsius. Cloud point is a measurementcomplementary to the pour point, and is expressed as a temperature atwhich a sample of the lubricant base oil begins to develop a haze undercarefully specified conditions. Cloud point may be determined by, forexample, ASTM D 5773-10. Fischer-Tropsch base oils having pour-cloudpoint spreads below about 35° C. are desirable. The pour-cloud pointspreads of the present Fischer-Tropsch base oils are generally less thanabout 35° C., preferably less than about 25° C., more preferably lessthan about 10° C. The cloud points are generally in the range of +30 to−30° C.

As noted previously, the Fischer-Tropsch base oils may be blended withother base oils to improve or modify their properties (e.g., viscosityindex, oxidation stability, pour point, sulfur content, tractioncoefficient, or Noack volatility). Examples of base oils that may beblended with the Fischer-Tropsch base oils are conventional Group I baseoils, conventional Group II base oils, conventional Group III base oils,other Fischer-Tropsch base oils, isomerized petroleum wax,polyalphaolefins, polyinternalolefins, oligomerized olefins fromFischer-Tropsch derived feed, diesters, polyol esters, phosphate esters,alkylated aromatics, alkylated cycloparaffins, and mixtures thereof. Theamount blended, however, is generally a minor amount so that the wear,friction and extreme pressure properties are not adversely affected.

During Fischer-Tropsch synthesis, liquid and gaseous hydrocarbons areformed by contacting a synthesis gas (syngas) comprising a mixture ofhydrogen and carbon monoxide with a Fischer-Tropsch catalyst undersuitable temperature and pressure reactive conditions. TheFischer-Tropsch reaction is typically conducted at temperatures of fromabout 300° to about 700° F. (about 150° to about 370° C.) preferablyfrom about 400° to about 550° F. (about 205° to about 230° C.);pressures of from about 10 to about 600 psia, (0.7 to 41 bars)preferably 30 to 300 psia, (2 to 21 bars) and catalyst space velocitiesof from about 100 to about 10,000 cc/g/hr., preferably 300 to 3,000cc/g/hr.

The products from the Fischer-Tropsch synthesis may range from C₁ toC₂₀₀ plus hydrocarbons, with a majority in the C₅ to C₁₀₀ plus range.Fischer-Tropsch synthesis may be viewed as a polymerization reaction.Applying polymerization kinetics, a simple one parameter equation candescribe the entire product distribution, referred to as theAnderson-Shultz-Flory (ASF) distribution:

W _(n)=(1−α² ×n×α ^(n-1)

Where W_(n) is the weight fraction of product with carbon number n, andα is the ASF chain growth probability. The higher the value of α, thelonger the average chain length.

The Fischer-Tropsch reaction can be conducted in a variety of reactortypes, such as, for example, fixed bed reactors containing one or morecatalyst beds, slurry reactors, fluidized bed reactors, or a combinationof different types of reactors. Such reaction processes and reactors arewell known and documented in the literature. The slurry Fischer-Tropschprocess, which is preferred in the practice of the invention, utilizessuperior heat (and mass) transfer characteristics for the stronglyexothermic synthesis reaction and is able to produce relatively highmolecular weight, paraffinic hydrocarbons when using a cobalt catalyst.In the slurry process, a syngas comprising a mixture of hydrogen andcarbon monoxide is bubbled up as a third phase through a slurry whichcomprises a particulate Fischer-Tropsch type hydrocarbon synthesiscatalyst dispersed and suspended in a slurry liquid comprisinghydrocarbon products of the synthesis reaction which are liquid underthe reaction conditions. The mole ratio of the hydrogen to the carbonmonoxide may broadly range from about 0.5 to about 4, but is moretypically within the range of from about 0.7 to about 2.75 andpreferably from about 0.7 to about 2.5. A particularly preferredFischer-Tropsch process is taught in EP0609079, also completelyincorporated herein by reference for all purposes.

Suitable Fischer-Tropsch catalysts comprise one or more Group VIIIcatalytic metals such as Fe, Ni, Co, Ru and Re, with cobalt beingpreferred. Additionally, a suitable catalyst may contain a promoter.Thus, a preferred Fischer-Tropsch catalyst comprises effective amountsof cobalt and one or more of Re, Ru, Pt, Fe, Ni, Th, Zr, Hf, U, Mg andLa on a suitable inorganic support material, preferably one whichcomprises one or more refractory metal oxides. In general, the amount ofcobalt present in the catalyst is between about 1 and about 50 weightpercent of the total catalyst composition. The catalysts can alsocontain basic oxide promoters such as ThO₂, La₂O₃, MgO, and TiO₂,promoters such as ZrO₂, noble metals (Pt, Pd, Ru, Rh, Os, Ir), coinagemetals (Cu, Ag, Au), and other transition metals such as Fe, Mn, Ni, andRe. Suitable support materials include alumina, silica, magnesia andtitania, or mixtures thereof. Preferred supports for cobalt containingcatalysts comprise titania. Useful catalysts and their preparation areknown and illustrated in U.S. Pat. No. 4,568,663, which is intended tobe illustrative but non-limiting relative to catalyst selection.

In one embodiment, the substantially paraffinic wax feed is dewaxed byhydroisomerization dewaxing at conditions sufficient to produce aFischer-Tropsch base oil with a desired composition of cycloparaffinsand a moderate pour point. For example, the conditions forhydroisomerization dewaxing can be controlled such that the conversionof the compounds boiling above about 700° F. in the wax feed tocompounds boiling below about 700° F. is maintained between about 10 wt% and 50 wt %, preferably between 15 wt % and 45 wt %.Hydroisomerization dewaxing is intended to improve the cold flowproperties of a lubricating base oil by the selective addition ofbranching into the molecular structure. Hydroisomerization dewaxingideally will achieve high conversion levels of waxy feed to non-waxyiso-paraffins while at the same time minimizing the conversion bycracking.

In one embodiment, hydroisomerization is conducted using a shapeselective intermediate pore size molecular sieve. Hydroisomerizationcatalysts that can be used can comprise a shape selective intermediatepore size molecular sieve and a catalytically active metal hydrogenationcomponent on a refractory oxide support. The phrase “intermediate poresize,” as used herein means a crystallographic free diameter in therange of from about 3.9 to about 7.1 Angstrom when the porous inorganicoxide is in the calcined form. The shape selective intermediate poresize molecular sieves can be 1-D 10-, 11- or 12-ring molecular sieves.In one embodiment, the molecular sieves are of the 1-D 10-ring variety,where 10-(or 11- or 12-) ring molecular sieves have 10 (or 11 or 12)tetrahedrally-coordinated atoms (T-atoms) joined by oxygens. In the 1-Dmolecular sieve, the 10-ring (or larger) pores are parallel with eachother, and do not interconnect. Note, however, that 1-D 10-ringmolecular sieves which meet the broader definition of the intermediatepore size molecular sieve but include intersecting pores having8-membered rings may also be encompassed within the definition of themolecular sieve of the present invention. The classification ofintrazeolite channels as 1-D, 2-D and 3-D is set forth by R. M. Barrerin Zeolites, Science and Technology, edited by F. R. Rodrigues, L. D.Rollman and C. Naccache, NATO ASI Series, 1984 which classification isincorporated in its entirety by reference (see particularly page 75).

In one embodiment, the shape selective intermediate pore size molecularsieves used for hydroisomerization dewaxing are based upon aluminumphosphates, such as SAPO-11, SAPO-31, and SAPO-41. In anotherembodiment, the shape selective intermediate pore size molecular sievesused for hydroisomerization dewaxing are selected from SAPO-11 andSAPO-31. In another embodiment, SM-3 is the shape selective intermediatepore sized molecular sieve used for hydroisomerization dewaxing. SM-3has a crystalline structure falling within that of the SAPO-11 molecularsieves. The preparation of SM-3 and its unique characteristics aredescribed in U.S. Pat. Nos. 4,943,424 and 5,158,665. Other shapeselective intermediate pore size molecular sieves used forhydroisomerization dewaxing are zeolites, such as ZSM-22, ZSM-23,ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, and ferrierite. In oneembodiment, the molecular sieve used for hydroisomerization dewaxing isselected from SSZ-32, SSZ-32X, ZSM-23, and mixtures thereof. SSZ-32X isdescribed in U.S. Pat. No. 7,569,507 and U.S. Pat. No. 7,468,126, hereinincorporated in their entireties.

In one embodiment, the intermediate pore size molecular sieve ischaracterized by selected crystallographic free diameters of thechannels, selected crystallite size (corresponding to selected channellength), and selected acidity. In one embodiment, the crystallographicfree diameters of the channels of the molecular sieves are in the rangeof from about 3.9 to about 7.1 Angstrom, having a maximumcrystallographic free diameter of not more than 7.1 and a minimumcrystallographic free diameter of not less than 3.9 Angstrom. In oneembodiment, the maximum crystallographic free diameter is not more than7.1 and the minimum crystallographic free diameter is not less than 4.0Angstrom. In another embodiment, the maximum crystallographic freediameter is not more than 6.5 and the minimum crystallographic freediameter is not less than 4.0 Angstrom. The crystallographic freediameters of the channels of molecular sieves are published in the“Atlas of Zeolite Framework Types”, Fifth Revised Edition, 2001, by Ch.Baerlocher, W. M. Meier, and D. H. Olson, Elsevier, pp 10 15, which isincorporated herein by reference.

If the crystallographic free diameters of the channels of a molecularsieve are unknown, the effective pore size of the molecular sieve can bemeasured using standard adsorption techniques and hydrocarbonaceouscompounds of known minimum kinetic diameters. See Breck, ZeoliteMolecular Sieves, 1974 (especially Chapter 8); Anderson et al. J.Catalysis 58, 114 (1979); and U.S. Pat. No. 4,440,871, the pertinentportions of which are incorporated herein by reference. In performingadsorption measurements to determine pore size, standard techniques areused. It is convenient to consider a particular molecule as excluded ifdoes not reach at least 95% of its equilibrium adsorption value on themolecular sieve in less than about 10 minutes (p/po=0.5; 25° C.).Intermediate pore size molecular sieves will typically admit moleculeshaving kinetic diameters of 5.3 to 6.5 Angstrom with little hindrance.

In one embodiment, the hydroisomerization dewaxing catalyst has a MTTframework type and the catalyst contains at least one metal selectedfrom the group consisting of Ca, Cr, Mg, La, Na, Pr, Sr, K, and ND, andat least one Group VIII metal. These catalysts are described in USPatent Publication No. US20080083657.

In one embodiment, the hydroisomerization dewaxing catalysts havesufficient acidity so that 0.5 grams thereof when positioned in a tubereactor converts at least 50% of hexadecane at 370° C., pressure of 1200psig, a hydrogen flow of 160 ml/min, and a feed rate of 1 ml/hr. In oneembodiment, the catalyst also exhibits isomerization selectivity of 40percent or greater (isomerization selectivity is determined as follows:100×(weight % branched C₁₆ in product)/(weight % branched C₁₆ inproduct+weight % C₁₃-in product) when used under conditions leading to96% conversion of normal hexadecane (n-C₁₆) to other species.

Hydroisomerization dewaxing catalysts can comprise a catalyticallyactive hydrogenation noble metal. The presence of a catalytically activehydrogenation metal can lead to product improvement, especially toimprovements in viscosity index and oxidation stability. The noblemetals platinum and palladium can be used, either alone or incombination. In one embodiment, if platinum and/or palladium is used,the total amount of active hydrogenation metal is in the range of 0.1 to5 weight percent of the total catalyst, or from 0.1 to 2 weight percent,and in some embodiments will not exceed 10 weight percent.

In one embodiment, the refractory oxide support can be selected fromthose oxide supports which are conventionally used for catalysts,including silica, alumina, silica-alumina, magnesia, titania, andcombinations thereof.

In one embodiment, the conditions for hydroisomerization dewaxing dependon the feed used, the catalyst used, whether or not the catalyst issulfided, the desired yield, and the desired properties of the lubricantbase oil. In one embodiment, conditions under which thehydroisomerization dewaxing can be carried out include temperatures fromabout 600° F. to about 750° F. (315° C. to about 399° C.), such as fromabout 600° F. to about 700° F. (315° C. to about 371° C.); and pressuresfrom about 15 to 3000 psig, such as from 100 to 2500 psig. Thehydroisomerization dewaxing pressures in this context refer to thehydrogen partial pressure within the hydroisomerization reactor,although the hydrogen partial pressure is substantially the same (ornearly the same) as the total pressure. The liquid hourly space velocityduring contacting can be from about 0.1 to 20 hr-1, for example, fromabout 0.1 to about 5 hr-1. In one embodiment, the hydrogen tohydrocarbon ratio falls within a range from about 1.0 to about 50 molesH₂ per mole hydrocarbon, such as from about 10 to about 20 moles H₂ permole hydrocarbon. Suitable conditions for performing hydroisomerizationare described in U.S. Pat. Nos. 5,282,958 and 5,135,638, the contents ofwhich are incorporated by reference in their entirety.

In one embodiment, hydrogen is present in the reaction zone during thehydroisomerization dewaxing process. For example, the hydrogen to feedratio can be from about 0.5 to 30 MSCF/bbl (thousand standard cubic feetper barrel), or from about 1 to about MSCF/bbl. In one embodiment,hydrogen will be separated from the product and recycled to the reactionzone.

Hydrotreating refers to a catalytic process, usually carried out in thepresence of free hydrogen, in which the primary purpose is the removalof various metal contaminants, such as arsenic, aluminum, and cobalt;heteroatoms, such as sulfur and nitrogen; oxygenates; or aromatics fromthe feed stock. In one embodiment, in hydrotreating operations crackingof the hydrocarbon molecules, i.e., breaking the larger hydrocarbonmolecules into smaller hydrocarbon molecules, is minimized, and theunsaturated hydrocarbons are either fully or partially hydrogenated. Inone embodiment, waxy feed that is used to make the Fischer-Tropsch baseoil is hydrotreated prior to hydroisomerization dewaxing.

Catalysts used in carrying out hydrotreating operations are well knownin the art. See for example U.S. Pat. Nos. 4,347,121 and 4,810,357, thecontents of which are hereby incorporated by reference in theirentirety, for general descriptions of hydrotreating, hydrocracking, andof typical catalysts used in each of the processes. Suitable catalystsinclude noble metals from Group VIIIA (according to the 1975 rules ofthe International Union of Pure and Applied Chemistry), such as platinumor palladium on an alumina or siliceous matrix, and Group VIII and GroupVIB, such as nickel-molybdenum or nickel-tin on an alumina or siliceousmatrix. U.S. Pat. No. 3,852,207 describes a suitable noble metalcatalyst and mild conditions. Other suitable catalysts are described,for example, in U.S. Pat. Nos. 4,157,294 and 3,904,513. In oneembodiment, the non-noble hydrogenation metals, such asnickel-molybdenum, can be present in the final catalyst composition asoxides, and can also be employed in their reduced or sulfided forms whensuch sulfide compounds are readily formed from the particular metalinvolved. In one embodiment, the non-noble metal catalyst compositionscontain in excess of about 5 weight percent, such as from about 5 toabout 40 weight percent molybdenum and/or tungsten, and can contain atleast about 0.5, such as from about 1 to about 15 weight percent ofnickel and/or cobalt determined as the corresponding oxides. In oneembodiment, catalysts containing noble metals, such as platinum, cancontain in excess of 0.01 percent metal, e.g., between about 0.1 and 1.0percent metal. In other embodiments, combinations of noble metals canalso be used, such as mixtures of platinum and palladium.

In one embodiment, hydrotreating conditions vary over a wide range. Inone embodiment, the overall LHSV is about 0.25 to 2.0, such as about 0.5to 1.5. In one embodiment, the hydrogen partial pressure is greater than200 psia, and can be from about 500 psia to about 2000 psia. In oneembodiment, hydrogen recirculation rates can be greater than 50 SCF/Bbl,such as between 1000 and 5000 SCF/Bbl. In one embodiment, temperaturesin the hydrotreating reactor can range from about 300° F. to about 750degrees F. (about 150° C. to about 400° C.), or from 450° F. to 725° F.(230° C. to 385° C.).

In one embodiment, hydrotreating is used as a step followinghydroisomerization dewaxing in the lubricant base oil manufacturingprocess to make the Fischer-Tropsch base oil. This step, herein calledhydrofinishing, is intended to improve the oxidation stability, UVstability, and appearance of the product by removing traces ofaromatics, olefins, color bodies, and solvents. As used in thisdisclosure, the term UV stability refers to the stability of thelubricating base oil or the finished lubricant when exposed to UV lightand oxygen. Instability is indicated when a visible precipitate forms,usually seen as floc or cloudiness, or a darker color develops uponexposure to ultraviolet light and air. A general description ofhydrofinishing may be found in U.S. Pat. Nos. 3,852,207 and 4,673,487.Clay treating to remove these impurities is an alternative final processstep.

Optionally, the process of preparing a Fischer-Tropsch base oil mayinclude fractionating of the substantially paraffinic wax feed prior tohydroisomerization dewaxing, or fractionating of the lubricating baseoil. The fractionation of the substantially paraffinic wax feed orlubricating base oil into distillate fractions is generally accomplishedby either atmospheric or vacuum distillation, or by a combination ofatmospheric and vacuum distillation. Atmospheric distillation istypically used to separate the lighter distillate fractions, such asnaphtha and middle distillates, from a bottoms fraction having aninitial boiling point above about 600° F. to about 750° F. (about 315°C. to about 399° C.). At higher temperatures thermal cracking of thehydrocarbons may take place leading to fouling of the equipment and tolower yields of the heavier cuts. Vacuum distillation is typically usedto separate the higher boiling material, such as the lubricating baseoil fractions, into different boiling range cuts. Fractionating thelubricating base oil into different boiling range cuts enables thelubricating base oil manufacturing plant to produce more than one grade,or viscosity, of lubricating base oil.

Solvent dewaxing may be optionally used to remove small amounts ofremaining waxy molecules from the lubricating base oil afterhydroisomerization dewaxing. Solvent dewaxing is done by dissolving thelubricating base oil in a solvent, such as methyl ethyl ketone, methyliso-butyl ketone, or toluene, or precipitating the wax molecules asdiscussed in Chemical Technology of Petroleum, 3rd Edition, WilliamGruse and Donald Stevens, McGraw-Hill Book Company, Inc., New York,1960, pages 566 to 570. See also U.S. Pat. Nos. 4,477,333, 3,773,650 and3,775,288.

The Fischer-Tropsch base oils used in preparing the present lubricatingoil compositions can have low levels of unsaturation. In one embodiment,the level of unsaturation is less that 20 weight percent, as determinedby elution column chromatography, ASTM D 2549-02 (Reapproved 2007). Inanother embodiment, the level of unsaturations is from 5 to 50 wt %, orfrom 10 to 40 wt %.

Lubricating oils can come into direct contact with seals, gaskets, andother equipment components during use. Original equipment manufacturersand standards setting organizations set elastomer compatibilityspecifications for different types of finished lubricants. Examples ofelastomer compatibility tests are CEC L-39-T-96, and ASTM D 4289-03. AnASTM standard entitled “Standard Test Method and Suggested Limits ofDetermining the Compatibility of Elastomer Seals for IndustrialHydraulic Fluid Applications” is currently in development. Elastomercompatibility test procedures involve suspending a rubber specimen ofknown volume in the lubricating base oil or finished lubricant underfixed conditions of temperature and test duration. This is followed atthe end of the test by a second measurement of the volume to determinethe percentage swell that has occurred. Additional measurements may bemade of the changes in elongation at break and tensile strength.Depending on the rubber type and application, the test temperature mayvary significantly. The present lubricating oil compositions arecompatible with a broad number of elastomers, including but not limitedto the following: neoprene, nitrile (acrylonitrile butadiene),hydrogenated nitrile, polyacrylate, ethylene-acrylic, silicone,chlor-sulfonated polyethylene, ethylene-propylene copolymers,epichlorhydrin, fluorocarbon, perfluoroether, and PTFE.

The process for manufacturing the lubricating oil composition includesthe step of blending the Fischer-Tropsch base oil with at least thefriction modifier based on synthetic esters and a sulfurized extremepressure agent. The friction modifier based on a synthetic esterprovides a lower coefficient of friction to the lubricating oil blendedwith it. Examples of synthetic esters are diesters, phthalates,trimellitates, pyromellitates, dimerates, polyols, polyoleates, andcomplex polyols. In one embodiment the synthetic ester is made from amultifunctional alcohols, such as neopentylglycol (NPG),trimethylolpropane (TMP, pentaerythritol (PE), or mixtures thereof. Inone embodiment, the synthetic ester is a diester or triester made byprocesses disclosed in US20080194444, U.S. Pat. No. 7,544,645,US20090088351, US20100311625, US20090198075, or U.S. patent applicationSer. No. 12/962,193, filed Dec. 7, 2010.

In one embodiment the friction modifier based on a synthetic estercomprises long, slim molecules with a straight hydrocarbon chainconsisting of at least 10 carbon atoms and a polar group at one end. Inone embodiment, the synthetic ester is a partial ester, for exampleglycerol mono oleate. In another embodiment, the synthetic ester is afatty acid sorbitan ester. In another embodiment, the synthetic ester isa borated or unborated fatty acid ester of glycerol. In one embodiment,the synthetic ester is an ester of pentaethrythritol and C6-C20 fattyacids. In another embodiment, the synthetic ester is a ester frompolyol, and C12-C28 branched or cyclic fatty acids.

A sulfurized extreme pressure agent is a sulfur carrier that containssulfur in its oxidation state 0 or −1, where the sulfur atom is boundeither to a hydrocarbon or to another sulfur atoms, and does not containother hetero atoms except oxygen. The sulfurized extreme pressure can bemade by adding sulfur to different kinds of unsaturated,double-bond-containing compounds such as olefins, natural esters,acrylates, and others. Some examples of sulfurized extreme pressureagents include: sulfurized isobutene, active-type sulfurized olefins,inactive sulfurized alpha olefins, inactive sulfurized alpha olefins,sulfurized synthetic esters, sulfurized fatty oil, and sulfurized fattyoil and olefin mixtures.

An emulsifier and copper corrosion inhibitor are also additives that canbe used in the lubricating oil. Other additives which can be blendedwith the Fischer-Tropsch base oil to form the lubricating oilcomposition include those which are intended to improve other certainproperties of the finished lubricant. Typical additives include, forexample, anti-wear additives, EP agents, detergents, dispersants,antioxidants, pour point depressants, Viscosity Index improvers,viscosity modifiers, antifoaming agents, rust inhibitors, seal swellagents, wetting agents, lubricity improvers, metal deactivators, gellingagents, tackiness agents, bactericides, fluid-loss additives, colorants,and the like. In one embodiment, the total amount of additive in thelubricating oil composition is within the range of 0.1 to 30 weightpercent. In one embodiment, the amount of Fischer-Tropsch base oil inthe lubricating oil composition is between 70 and 99.9 weight percent,such as between 90 and 99 weight percent. Lubricant additive supplierswill provide information on effective amounts of their individualadditives or additive packages to be blended with lubricating base oilsto make finished lubricants.

Another desirable additive to be used in the lubricating oil compositionis a tackiness agent. A tackiness agent is a solution of polymers inoil. The polymers can be of a molecular weight from 400,000 to4,000,000. Examples of polymers used in tackiness agents arepolyisobutylene, olefin copolymers, natural rubber,polyisobutylene/acrylic co-polymers, and ethylene/propylene co-polymers.A demonstration of tackiness is the time-honored “finger test” where thetacky solution will draw a filament across the airspace as the fingersare pulled apart. The tacking quality would also make the presentlubricating oil composition suitable for once-through application, e.g.,lubrication of chain drives.

Overall, the extreme pressure chemistry of the present lubricating oilcomposition makes it an excellent industrial extreme-pressure gearlubricant. The lubricating oil composition, therefore finds an importantapplication in a system of enclosed industrial gears. As well, thelubricating oil composition finds application as an excellent stampingand drawing fluid for the metal working industry.

The lubricating oil has excellent load-carrying properties. In oneembodiment, the lubricating oil exhibits medium or high levels ofextreme-pressure properties. In one embodiment, the lubricating oil hasa true load value at which failure occurs in the Falex Pin and Vee BlockMethod Test (ASTM D3233-93[Reapproved 2009]^(ε1), Test Method A, of atleast 3500 lb, at least 3600 lb, at least 3700 lb, or at least 3800 lb.

In one embodiment, the lubricating oil has a passing result in the4-hour Tort B rust test, according to ASTM D665-06 Procedure B, usingsynthetic seawater. In another embodiment, the lubricating oil has botha passing result in the 4-hour Tort B rust test and a passing result inthe 24-hour Tort B rust test. ASTM D665-06 is the Standard Test Methodfor Rust-Preventing Characteristics of Inhibited Mineral Oil in thePresence of Water.

In one embodiment, the lubricating oil has a VI greater than 120,greater than 130, greater than 140, or greater than 150. VI isdetermined using ASTM D 2270-10, the Standard Practice for CalculatingViscosity Index from Kinematic Viscosity at 40 and 100° C.

In one embodiment, the lubricating oil has a color less than 1.0 or lessthan 0.5, according to ASTM D 1500-07, the Standard Test Method for ASTMColor of Petroleum Products (ASTM Color Scale).

In one embodiment the lubricating oil has an of ISO viscosity grade ofISO 32 or higher. In another embodiment, the lubricating oil has an ISOviscosity grade from ISO 32 to ISO 680. ISO viscosity grades aredetermined according to the following table:

Limits of Kinematic ISO Average Kinematic Viscosity at 40° C. ViscosityViscosity at 40° C. mm²/s Grade mm²/s min. max. ISO VG 32 32 28.8 35.2ISO VG 46 46 41.4 50.6 ISO VG 68 68 61.2 74.8 ISO VG 100 100 90 110 ISOVG 150 150 135 165 ISO VG 220 220 198 242 ISO VG 320 320 288 352 ISO VG460 460 414 506 ISO VG 680 612 612 748 ISO VG 1000 1000 900 1100 ISO VG1500 1500 1350 1650

Example

A series of ISO 46 grade lubricating oils were prepared using acommercially available additive package containing a friction modifierbased on synthetic esters and sulfurized extreme pressure agents.Comparative lubricants (non-Fischer-Tropsch) from API Groups I, II, IIIand IV were used and compared to the Fischer-Tropsch-based lubricatingoil. The additive package was solubilized in the Fischer-Tropsch basedlubricating oil at least as well as, if not better than, the comparativelubricants.

The specifications for Lubricant Base Oils defined in the APIInterchange Guidelines (API Publication 1509) using sulfur content,saturates content, and viscosity index, are shown below in Table I:

TABLE I Group Sulfur, ppm Saturates, % VI I >300 and/or <90 80-120 II≦300 and ≧90 80-120 III ≦300 and ≧90 >120 IV All Polyalphaolefins V AllStocks Not Included in Groups I-IV

Facilities that make Group I lubricant base oils typically use solventsto extract the lower viscosity index (VI) components and increase the VIof the crude to the specifications desired. These solvents are typicallyphenol or furfural. Solvent extraction gives a product with less than90% saturates and more than 300 ppm sulfur. The majority of thelubricant production in the world is in the Group I category.

Facilities that make Group II lubricant base oils typically employhydroprocessing such as hydrocracking or severe hydrotreating toincrease the VI of the crude oil to the specification value. The use ofhydroprocessing typically increases the saturate content above 90 andreduces the sulfur below 300 ppm. Approximately 10% of the lubricantbase oil production in the world is in the Group II category, and about30% of U.S. production is Group II.

Facilities that make Group III lubricant base oils typically employ waxisomerization technology to make very high VI products. Since thestarting feed is waxy vacuum gas oil (VGO) or wax which contains allsaturates and little sulfur, the Group III products have saturatecontents above 90 and sulfur contents below 300 ppm. Fischer-Tropsch waxis an ideal feed for a wax isomerization process to make Group IIIlubricant base oils. Only a small fraction of the world's lubricantsupply is in the Group III category.

Group IV lubricant base oils are derived by oligomerization of normalalpha olefins and are called poly alpha olefin (PAO) lubricant baseoils.

Below are results showing a Fischer-Tropsch based lubricating oil (E) tohave superior wear, friction and extreme pressure properties—as measuredby the Falex Pin and Vee Block Machine—compared to Group 1, Group II,Group III (mineral oil-derived) and PAO-based formulations. TheFischer-Tropsch based lubricating oil obtained a 3700 lb result on theFalex EP test. This was unexpected, and it demonstrated thatFischer-Tropsch base oils can be used to further reduce and optimize thefriction and extreme pressure properties of a lubricant.

ISO Viscosity Grade ISO 46 ISO 46 ISO 46 ISO 46 ISO 46 Identification AB C D E Base Oils - Group Type III - Method Mineral Fischer- Test (ASTM)I II Oil PAO (IV) Tropsch Kinematic Viscosity D445-10 44.65 44.04 44.1242.83 44.24 @40° C. Kinematic Viscosity D445-10 6.942 7.006 7.667 7.5618.106 @100° C. VI D2270-10 112 117 143 145 159 Color D1500-07 L1.0 L0.5L0.5 L0.5 L0.5 Appearance Bright, Bright, Barely Contains Barely nocloud, no cloud, detectable sediment detectable floc or floc or cloudcloud sediment sediment Copper Strip, 3 hrs at D130-10 3a 1b 1b 3a 1b100° C. Rust 4 hr/24 hr D665-06, P/P P/P P/P P/P P/P Procedure B FalexTrue Load, lbf D3233-93 3100 2500 2800 3500 3700 (Reapproved 2009)^(εl)Test Method A

Various modifications and alterations of this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of the invention. Other objects and advantages will becomeapparent to those skilled in the art from a review of the precedingdescription.

1. A lubricating oil composition for use in rotary pneumatic andreciprocating tools, comprising a Fischer-Tropsch base oil, a frictionmodifier based on a synthetic ester, and a sulfurized extreme pressureagent.
 2. The lubricating oil composition of claim 1, wherein thecomposition further comprises an emulsifier.
 3. The lubricating oilcomposition of claim 1, wherein the composition further comprises acopper corrosion inhibitor.
 4. The lubricating oil composition of claim2, wherein the composition further comprises a copper corrosioninhibitor.
 5. The lubricating oil composition of claim 1, wherein aViscosity Index (VI) of the Fischer-Tropsch base oil is at least
 120. 6.The lubricating oil composition of claim 5, wherein the Viscosity Index(VI) of the Fischer-Tropsch base oil is at least
 150. 7. The lubricatingoil composition of claim 1, wherein the Fischer-Tropsch base oil isblended with another Fischer-Tropsch base oil.
 8. The lubricating oilcomposition of claim 1, wherein the Fischer-Tropsch base oil has aviscosity of at least 120 and the composition further comprises anemulsifier and a copper corrosion inhibitor.
 9. The lubricating oilcomposition of claim 1, wherein the Fischer-Tropsch base oil comprisesat least 70 wt. % of the lubricating oil composition.
 10. Thelubricating oil composition of claim 1, wherein the Fischer-Tropsch baseoil comprises at least 90 wt. % of the lubricating oil composition. 11.The lubricating oil composition of claim 1, wherein the Fischer-Tropschbase oil comprises at least 95 wt. % of the lubricating oil composition.12. The lubricating oil composition of claim 1, wherein the compositionhas a true load value at which failure occurs in the Falex Pin and VeeBlock Method Test of at least 3600 lb.
 13. The lubricating oilcomposition of claim 1, wherein the composition has a true load value atwhich failure occurs in the Falex Pin and Vee Block Method Test of atleast 3700 lb.
 14. The lubricating oil composition of claim 1, whereinthe composition has a passing result in the 4-hour Tort B rust test. 15.The lubricating oil composition of claim 1, wherein the composition hasa passing result in the 24-hour Tort B rust test.
 16. The lubricatingoil composition of claim 1, wherein the composition has a VI greaterthan
 120. 17. The lubricating oil composition of claim 1, wherein thecomposition has a VI greater than
 150. 18. The lubricating oilcomposition of claim 1, wherein the composition has a color less than0.5.
 19. A rotary pneumatic or reciprocating tool, comprising thelubricating oil composition of claim 1 as its lubricating oil.
 20. Thetool of claim 19, wherein the tool is a rock drill.
 21. The tool ofclaim 19, wherein the tool is a jack hammer.
 22. A system of enclosedindustrial gears, comprising the lubricating oil composition of claim 1as the lubricant.